Best way to connect 3x18650's in a battery box

[Streak]

I bought one of these

http://www.ebay.com/itm/5V-2A-2-Dua...S_Cell_Phone_PDA_Chargers&hash=item1c3db97b9a

It requires for the batteries to be connected in parallel. I could solder them together but would prefer to have them removable.
Any clever ideas to achieve this?
There is not enough of a gap to insert springs.
I have a bunch of foil strips after harvesting 18650's from old laptop batteries but not sure inserting them will give a solid enough connection.

Thanks.

 

[CMAG]

If box is thick enough you may be able to drill, tap and use small set screws from outside to inside of box to secure (clamp) foil strips

 

[stoneboy]

As I can see from the picture, there are some white blocks in between the batteries and the wall. The white block seems like a spacing block. Could you try to remove it? You would get enough space if you just remove one side (two pieces).

Just be careful when you connect your foil strips to the batteries if you can not weld them. It would cause serious problem if the contact is not solid!